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Cacomitl Cat — Part 3

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H. Incisors grooved..... GEOMYS, 97-99

HH. Incisors not grooved..... THOMOMYS, 96

GG. Form not mole-like; fore feet normal.

H. Body heavy and thick-set, 12-20 inches long exclusive of tail; legs short.

I. Tail very broad, flat, covered with scales; teeth, i 1/1, c 0/0, p 1/1, m 3/3..... CASTOR, 145-150

II. Tail long and narrow, flattened vertically, and nearly naked teeth, i 1/1, c 0/0, p 0/0, m 3/3. FIBER, 121-127

III. Tail hairy; teeth, i 1/1, c 0/0, p 2/1-1/1 m 3/3.

J. Tail very short, less than the head. APLODONTIA, 150

JJ. Tail moderate, longer than the head, ARCTOMYS, 151-159

HH. Form mouse-like or rat-like; size not larger than a common rat (body less than 10 ins. without tail); teeth usually, i 1/1, c 0/0, p 0/0, m 3/3.

I. Pouches on the sides of the face opening near the mouth.

J. Tail very long; teeth as above. PERODIPUS, 100

JJ. Tail moderate; teeth, i 1/1, c 0/0, p 1/1, m 3/3. PEROGNATHUS, 100

II. No external cheek pouches.

J. Hind legs much longer than the front ones; tail exceeding head and body; teeth in one species, i 1/1, c 0/0, p 1/1, m 3/3....ZAPUS, 102-105

JJ. Hind legs not markedly longer than front ones.

K. Thick-set, short-legged, short-eared mice of the meadow mouse type.

L. Tail less than one-third the length of head and body, generally much less.

M. Upper incisors grooved. SYNAPTOMYS, 107-108

MM. Upper incisors not grooved.

N. Tail so short as to be barely visible beyond the hair.

O. Color mottled (white in winter). DICROSTONYX, 108

OO. Color tawny orange. LEMMUS, 110

NN. Tail plainly visible, usually about one inch long.

O. Molar teeth rooted (See p. 110).

P. Color dark-brown; teeth heavy..PHENACOMYS, 110

PP. Color rusty; teeth lighter. EVOTOMYS, 111-112

OO. Molars not rooted. MICROTUS, 112-120

LL. Tail equal to two-thirds the head and body.

M. Fur coarse; many buff hairs among the brown ones; molars rooted. SIGMODON, 128-129

MM. Fur fine uniform, like that of the Muskrat; molars not rooted. MICROTUS ALLENI, 120

KK. Slender with longer legs and prominent ears and eyes; tail always more than half the head and body (except Onychomys), generally much more.

L. Tubercles on molar teeth in three rows (introduced species)....MUS, 138-145

LL. Tubercles on the molars, if present, in two rows (native species).

M. Size large, rat-like; molars flat on top, divided into triangles. NEOTOMA, 127-128

MM. Size medium, rat-like; molars tuberculate; strongly resembling a young Common Rat. ORYZOMYS, 129-130

MMM. Size small; mouse-like.

N. Tail always more than half the head and body; often about equal.

O. Upper incisors grooved. REITHRODONTOMYS, 130-131

OO. Upper incisors not grooved. PEROMYSCUS, 136

NN. Tail short, less than half the head and body.... ONYCHOMYS, 136

HHH. Form squirrel-like; teeth, i 1/1, c 0/0, p 2/1, m 3/3.

I. An extensible fold of skin on the sides of the body for flying....SCIUROPTERUS, 176-178

II. No extensible skin for flying.

J. Burrowing animals; tail not bushy.

K. Tail very short, 1-3 to 1-4 head and body. CYNOMYS, 160

KK. Tail 1-3 to 1-2 head and body. SPERMOPHILUS, 161-162

KKK. Tail 1-2 head and body; body prominently striped..... TAMIAS, 162

JJ. Arboreal species, tail long and bushy. SCIURUS, 168-176

DD. Tooth row nearly continuous, leaving no large gap at the side of the jaw. Incisors small and always more than two.

E. Size small (less than seven inches long), fur always drab or iron gray, soft and silky; eyes rudimentary.

F. Fore feet flattened for digging (Moles).

G. A fleshy star on the nose; teeth, i 3/3, c 1/1, p 4/4, m 3/3. CONDYLURA, 190

GG. No fleshy star on the nose.

H. Tail naked; teeth, i 3/2, c 1/0, p 3/3, m 3/3....SCALOPS, 188

HH. Tail hairy; teeth, i 3/3, c 1/1, p 4/4, m 3/3. PARASCALOPS, 189

FF. Fore feet normal.

G. Tail short 1-4 the head and body; teeth, i 4/2-3/2, c 1/0, p 2/1, m 3/3..... BLARINA, 180-183

GG. Tail at least 1-2 the head and body; teeth, i 4/2, c 1/0, p 2/1, m 3/3..... SOREX, 184-187

EE. Size medium or large; eyes well developed.

F. Toes webbed.

G. Hind feet large and very different from the front ones, resembling flippers; teeth, i 3/2, c 1/1, p 3/3, m 1/2, LATAX, 223

GG. Feet all alike; teeth, i 3/3, c 1/1, p 4/3, m 1/2..LUTRA, 219-223

FF. Toes not webbed.

G. Toes, five on all feet.

H. Teeth, i 3/3, c 1/1, p 4/4, m 2/2.

I. Nose produced into a slender snout; tail obscurely ringed.....NASUA, 254

II. Nose not lengthened; tail strongly ringed with black and white.

J. Body thick-set; feet plantigrade. PROCYON, 247

JJ. Body slender, weasel-like; feet only partially plantigrade.....BASSARISCUS, 254